Several patents describe methods of defibrillation of a heart employing an implanted device, wherein at least two electrode-bearing leads are inserted through the superior vena cava/right atrium of a patient's heart and the leads lodged in the heart or its adjacent blood vessels.
U.S. Pat. No. 4,641,656 (Smits) describes such a method in conjunction with its FIG. 15, wherein separate electrodes are disposed in the apex of the right ventricle, in the right atrium, and optionally in the coronary sinus.
U.S. Pat. No. 4,727,877 (Kallok) describes a defibrillation method in which there is inserted a first lead bearing a first pair of electrodes, both of which are located in the right ventricle, and a second pair of electrodes located in the superior vena cava. A second lead, bearing an electrode at its distal end which is lodged in the coronary sinus, is inserted. The implanted device can deliver sequential pulses for purposes of the method of defibrillation.
U.S. Pat. No. 4,932,407 (Williams) describes a defibrillation method wherein a first lead having a distal defibrillation electrode is inserted into the right atrium, and a second lead bearing a distal defibrillation electrode at its distal end is inserted through the superior vena cava/right atrium into the coronary sinus and into the great vein.
U.S. Pat. No. 5,140,696 (Mehra) describes a method of defibrillation wherein a first lead having a distal defibrillation electrode is inserted into the right ventricle, and a second lead bearing a distal defibrillation electrode at its distal end is inserted through the superior vena cava/right atrium into the coronary sinus and into the great vein.
A number of designs are known for electrodes for use with devices and electrode-bearing leads that are inserted into the heart through the superior vena cava/right atrium, for example, U.S. Pat. No. 4,106,512 (Bisping), U.S. Pat. No. 5,042,143 (Holleman & Viktora) and U.S. Pat. No. 5,052,407 (Hauser, et al.).
The design and characteristics of implanted devices for use in methods of defibrillating, and generally also cardioverting, a human heart, optionally with the sensing and pacing thereof, are known in the prior art. Illustrative of these are U.S. Pat. No. 4,830,006 (Haluska, et al.), U.S. Pat. No. 4,969,463 (Dahl, et al.), U.S. Pat. No. 5,048,521 (Pless, et al.), U.S. Pat. No. 5,063,928 (Grevis, et al.), U.S. Pat. No. 5,117,824 (Keimel, et al.) and U.S. Pat. No. 5,129,392 (Bardy & Mehra). U.S. Pat. No. 4,953,551 (Mehra and Combs) describes a defibrillator having circuitry for generating biphasic pulses. These patents illustrate the variations in the circuitry, and the number of combinations and permutations in functions that can be performed, and the electrical wave forms and phases that may be employed.
An example of a currently available, specific implantable device is identified as PCD model 72171B. It is described in a technical manual entitled "THE PCD.RTM. TACHYARRHYTHMIA CONTROL DEVICE--Model 72171B--An Implementable Device For The Control Of Ventricular Arrhythmias Through Pacing, Cardioversion, And Defibrillation," 74 pp., copyright 1990 by Medtronic, Inc., Minneapolis, Minn. 55432.
A number of patents describe various wave forms, electrical phases of the shock being administered, and the sequences of the shocks. Illustrative of these are U.S. Pat. No. 4,548,203 (Tacker, et al. ), U.S. Pat. No. 4,944,300 (Saksena) describing bi-directional shocks, and the above-identified U.S. Pat. No. 4,969,463 (Dahl, et al.).
The disclosure of each of the prior art references identified in the four preceding paragraphs are herewith incorporated by this express reference to them.